C12.19 is an ANSI standard for extracting and organizing electric utility meter data in a tabular form, and the information arranged in a specific format to facilitate further processing.
C12.18 is an ANSI protocol specification for a transport session between a server (identified as meter-reading application) and a client C12.19 utility meter, and includes making requests to and receiving from a C12.19 meter specific aspects of the data contained in the C12.19 data tables, stored in the meter.